From 70d536eddf2bab82e428ea397dec8b4093c9f3c1 Mon Sep 17 00:00:00 2001
From: Rainer Schuetze <r.sagitario@gmx.de>
Date: Sun, 8 Oct 2017 15:10:56 +0200
Subject: [PATCH 1/2] fix Issue 17876 - moved bad assertion that failed for
 arrays of arrays with mixed modifiers to the memcmp version which should work
 on values anyway. Also fixed bad comparison via memcmp only comparing first
 element.

---
 src/object.d | 33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/src/object.d b/src/object.d
index 3b7e4e89f5..5250a571a6 100644
--- a/src/object.d
+++ b/src/object.d
@@ -3459,9 +3459,8 @@ if (!__traits(isScalar, T1))
     import core.internal.traits : Unqual;
     alias U1 = Unqual!T1;
     alias U2 = Unqual!T2;
-    static assert(is(U1 == U2), "Internal error.");
 
-    static if (is(U1 == void))
+    static if (is(U1 == void) && is(U2 == void))
         static @trusted ref inout(ubyte) at(inout(void)[] r, size_t i) { return (cast(inout(ubyte)*) r.ptr)[i]; }
     else
         static @trusted ref R at(R)(R[] r, size_t i) { return r.ptr[i]; }
@@ -3492,8 +3491,11 @@ if (!__traits(isScalar, T1))
         {
             // TODO: fix this legacy bad behavior, see
             // https://issues.dlang.org/show_bug.cgi?id=17244
+            static assert(is(U1 == U2), "Internal error.");
             import core.stdc.string : memcmp;
-            return (() @trusted => memcmp(&at(s1, u), &at(s2, u), U1.sizeof))();
+            auto c = (() @trusted => memcmp(&at(s1, u), &at(s2, u), U1.sizeof))();
+            if (c != 0)
+                return c;
         }
     }
     return s1.length < s2.length ? -1 : (s1.length > s2.length);
@@ -3552,9 +3554,15 @@ if (!__traits(isScalar, T1))
     {
         T[2] a = [T.max, T.max];
         T[2] b = [T.min_normal, T.min_normal];
+        T[2] c = [T.max, T.min_normal];
+        T[1] d = [T.max];
 
         assert(__cmp(a, b) > 0);
         assert(__cmp(b, a) < 0);
+        assert(__cmp(a, c) > 0);
+        assert(__cmp(a, d) > 0);
+        assert(__cmp(d, c) < 0);
+        assert(__cmp(c, c) == 0);
     }
 
     compareMinMax!real;
@@ -3588,6 +3596,24 @@ if (!__traits(isScalar, T1))
     assert(__cmp(b, a) < 0);
 }
 
+// arrays of arrays with mixed modifiers
+@safe unittest
+{
+    // https://issues.dlang.org/show_bug.cgi?id=17876
+    bool less1(immutable size_t[][] a, size_t[][] b) { return a < b; }
+    bool less2(const void[][] a, void[][] b) { return a < b; }
+    bool less3(inout size_t[][] a, size_t[][] b) { return a < b; }
+
+    immutable size_t[][] a = [[1, 2], [3, 4]];
+    size_t[][] b = [[1, 2], [3, 5]];
+    assert(less1(a, b));
+    assert(less3(a, b));
+
+    auto va = [cast(immutable void[])a[0], a[1]];
+    auto vb = [cast(void[])b[0], b[1]];
+    assert(less2(va, vb));
+}
+
 // objects
 @safe unittest
 {
@@ -3628,6 +3654,7 @@ if (!__traits(isScalar, T1))
 
     assert(__cmp([c1, c1][], [c2, c2][]) < 0);
     assert(__cmp([c2, c2], [c1, c1]) > 0);
+    assert(__cmp([c2, c2], [c2, c1]) > 0);
 }
 
 // Compiler hook into the runtime implementation of array (vector) operations.

From 28d4ef871ebfaf86537468d55b8aae9fc3160cec Mon Sep 17 00:00:00 2001
From: Rainer Schuetze <r.sagitario@gmx.de>
Date: Mon, 9 Oct 2017 08:33:27 +0200
Subject: [PATCH 2/2] add constraint that both arguments are not arrays of
 scalars

---
 src/object.d | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/object.d b/src/object.d
index 5250a571a6..e3b9a08ead 100644
--- a/src/object.d
+++ b/src/object.d
@@ -3454,7 +3454,7 @@ if (__traits(isScalar, T))
 // comparisons in the semantic analysis phase of CmpExp. The ordering
 // comparison is lowered to a call to this template.
 int __cmp(T1, T2)(T1[] s1, T2[] s2)
-if (!__traits(isScalar, T1))
+if (!__traits(isScalar, T1) && !__traits(isScalar, T2))
 {
     import core.internal.traits : Unqual;
     alias U1 = Unqual!T1;